We're trying to savor the last little bit of summer with this cake. It's light, lime-y, and perfectly coconut-y. Not to mention it's summer in a cake, so you can have summer in your house year round!
Preheat oven to 350F. Grease and line 2 6-inch cake pans1. Cream together the butter and sugar for 5 minutes. While the butter & sugar are creaming, whisk together the dry ingredients (flour, salt, and baking powder). Set aside
When the butter and sugar are creamed, add the eggs and yolks, one at a time, beating well after each addition, and scraping down the bowl occasionally. Add in the vanilla and coconut flavorings.
Add in 1/3 of the dry ingredients, mixing just until combined. Add in 1/2 of the coconut milk, mixing just until combined. Mix in another 1/3 of the dry ingredients, the last of the milk, then the last 1/3 of the dry ingredients, scraping down the sides and bottom of the bowl frequently.
Divide the batter evenly into the 2 prepared pans and bake for 35-45 minutes or until a toothpick inserted into the center of the cake comes out clean. Let cool 10 minutes before removing from pans and cool completely before frosting.
Cream together the butter and vanilla until light and fluffy. Add the powdered sugar one cup at a time, beating well after each cup is added. Add the lime juice (start with 2 tbsp, depending on the consistency you want, you may need 2 more) and lime zest, beating until buttercream is light and smooth.
Assemble the cakes, use the shredded coconut to coat the outside of the cake.